This invention relates to apparatus for liquid portioning and/or liquid transferring and specifically to a multichannel pipette and to replaceable tip containers for use with such a multichannel pipette.
In many laboratory determinations, apparatus is needed to transfer small precisely measured amounts of liquid from one tube into another. The system must be simple, rapid, economical, and precise. Transfer of small liquid quantities from one container into another has increased in laboratory applications particularly in connection with many liquid dosages and diluting series utilized in Bacteriology, Immunohaematology, Mycology, Mycoplasma, Parasitology, Rickettsia, Serology, Virology and V.D. Serology.
Liquid transfer may of course be performed in single tube pipettes either of the simple glass tube type or of the adjustable automatic type. When it is desirable to transfer given amounts of liquid from and to a multiplicity of sample containers it is far more economical to utilize apparatus which can transfer several samples simultaneously.
There are prior art systems which permit the transfer of more than one sample. In the system related to the registered trademark "Cooke Microtiter," a plate is used that has 8.times.12 pits, and the titration from one pit into another is performed by means of one or several microdiluters. These single microdiluters are either held in the hand, or several of them are held in a device which is handheld. Alternatively, they may be mounted in an automatic device placed in a machine. The mixing of the liquid in a pit is performed by rotating the microdiluter back and forth. The microdiluter transfers liquid so that the sample or reagent, due to capillary force, adheres to the calibrated tip portion of the microdiluter. Most commonly, in this system, volumes of 25 and 50 ul are used. The "Cooke Microtiter" involves several drawbacks:
The microdiluters of the system cannot be precisely calibrated, because the filling of the tip portion takes place by capillary force and the tip portion may not empty completely because of dirt, scratches in the glass or other mechanical problem in the tip portion of the device. The residue remaining in the microdiluters can result in contamination of other samples. Because of this, careful cleaning of the microdiluters is necessary after each use. This is expensive and can lead to errors if the cleaning substance is not thoroughly removed.
It is also difficult to vary the volume of this device since there are eight to twelve different volumes of microdiluters and the correct volume must be on hand for each application. This can be both cumbersome and expensive.
Another system on the market is a multichannel pipette sold under the trademark, "Finnpipette." Such a device is disclosed in U.S. Pat. No. 3,855,868. This device utilizes replaceable tip containers. To avoid the problem of contamination and also to avoid the necessity of an expensive and time consuming washing or cleaning after each use.
This device is adjustable over a wide range of volumes by a micrometer adjustment which can provide the necessary precision. It can also be conveniently held and operated in one hand.
Prior art tip container elements were formed in a structure in which several tip containers were connected by a rigid support or connection plate. A tip container element with such a rigid construction can be fitted to the tip cones of only one configuration of a multichannel pipette. Since a multichannel pipette may be constructed with different numbers and arrangements of tip cones depending upon the desired end use, flexibility is needed in the configuration of arrays of tip containers. The present invention provides this needed flexibility.
The present invention improves the above described prior art devices in several important ways. First, it provides an improved arrangement of replaceable tip containers which makes such tip containers easier to use with various multichannel pipette configurations. Second, it provides interchangeable precalibrated handles which can be attached to the body portion of a multichannel pipette. The use of such precalibrated handles avoids the necessity for the accurate setting of the micrometer adjustment of the prior art "Finnpipette" device and permits less skilled laboratory personnel to achieve accurate results quickly and easily.